The proposed study is concerned with the question of individual susceptibility to alcoholism. Substantial evidence suggests that genetic factors play a significant role in the genesis of at least some forms of alcoholism. It appears likely that the genes responsible must affect aspects of neural organization and/or alcohol metabolism, since it is ultimately by interacting with neural organization that alcohol has its psychological effects. Thus, it seems pertinent for studies attempting to shed light on the origins of alcoholism to employ measures directly sensitive to neural organization. The proposed study will focus on the P300 component of event-related potentials. P300 reflects both genetic and situational variables and it is thought to originate within brain structures regulating behaviors that are especially sensitive to alcohol. Moreover, evidence from recent studies clearly underscores the potential value of P300 research to the overall effort aimed at understanding susceptibility to alcoholism. The proposed study will examine the effects of acute alcohol intoxication on the scalp distribution (i.e., topography) of P300 as well as on its temporal-stability (i.e., over repeated testing) in individuals classified as either family history-positive (FH+) or negative (FH-) for alcoholism. Both men and women will be studied because there appears to be a differential susceptibility to alcoholism in the offspring of alcoholic biological parents depending upon sex of the offspring. Therefore, measures which are sensitive to "susceptibility" should discriminate between men and women with comparable genetic and environmental background. Specifically, it is hypothesized that FH+ men will differ significantly from FH- men and both FH+ and FH- women on spatiotemporal aspects of P300. In essence, the proposed study will examine P300 topography, a measure sensitive to neural organization, in groups differing in genetic risk for alcoholism. The subjects will be studied under both placebo and alcohol using a counterbalanced double-blind within-subject design. The goal of this research is to increase knowledge regarding individual susceptibility to alcoholism. It is anticipated that the information acquired will facilitate the development of methods for individual risk assessment and the design of more effective preventive interventions.